It was the last day of classes at the University of Calgary, celebrated for half a century as “Bermuda Shorts Day” and the beginning of new lives for graduates. There would be not merely a blood moon but a total eclipse of the moon that night. For some 20 young people in Canada on April 14, 2014 it was reason to party.

But for Matthew de Grood, it was reason to kill. And kill he did early on the morning of April 15, when he brutally stabbed to death five unsuspecting students in the leafy neighborhood of Brentwood.

Now Canada is riveted by his trial and the details that are emerging about his detachment from reality. In his mind, the full moon meant the end of days and was a call for a hero to slay the werewolves and vampires at the party — a call he answered. He admits he did it. He killed five people who had no reason to believe he was anything other than normal.

But he says he was not criminally responsible and thus not guilty. The legal question is whether he was suffering from a mental disorder at the time of the five slayings that rendered him incapable of appreciating the nature of what he did, or that what he did was wrong. If the court finds he wasn’t criminally responsible, he’ll be sent to a psychiatric facility for treatment rather than a prison for potentially five life sentences.

The trial, which began May 16, is also a study in psychosis, a detachment from reality that can manifest itself without warning especially in young people. The psychiatrists who examined him portray a rather abrupt divorce between de Grood and the real world which transformed him from the respectable son of a high-ranking police officer and a promising college grad bound for law school and a career as a prosecutor to, in his mind, a character in his own fantasy of conspiracies — conspiracies involving werewolves, vampires, an ancient Masonic cult called “Illuminati,” and for good measure, U.S. President Barack Obama, among others.

“He began to believe that he was the son of God and also the god Anubis,” reported court appointed forensic psychiatrist, Lenka Zedkova, of Alberta Edmonton Hospital. “He told his examiners that he had been reading about and believed that that there had been a conspiracy involving the Illuminati, werewolves and vampires, and that there was to be a war. He indicated to us that the music he was listening to also referred to him as a ‘hero’ citing the lyrics from one of the musical bands that he had posted on his Facebook account. He reported that he had believed he was Darth Vader and that his father was on the side of evil. He admitted that he began to believe that the evil side included Barack Obama and the Nazis. He believed that the world was to end April 14 because there was a full moon that night.”

Then there’s the human question, for the families of those slain and those following the trial - a dread that sends shivers up the spine: You go to a party, or your son or daughter goes to a party with people they think they know. Nice kids. College kids. And some of them don’t come back alive for inexplicable reasons. Had there been more people to kill, de Grood told psychiatrists, he would have killed them too.

Zachariah Rothwell, 21; Jordan Segura, 22; Josh Hunter, 23; Kaitlin Perras, 23 and Lawrence Hong, 27 — they’re all dead, at the bloody hands of de Grood, who stabbed each and every one of them without provocation, without warning, with an 8-inch kitchen knife he calmly removed from its wooden block.They had dreams too, as the court heard when it, unusually, allowed family members to stand and pay tribute to their lost loved ones. “He was passionate, and driven and he was building up to something,” said Miles Hong, the brother of Lawrence. “I never thought that there would be a tomorrow without my brother,” he said, according to the CBC.

“The word psychosis,” says the National Institute of Mental Health, “is used to describe conditions that affect the mind, where there has been some loss of contact with reality. When someone becomes ill in this way it is called a psychotic episode. During a period of psychosis, a person’s thoughts and perceptions are disturbed and the individual may have difficulty understanding what is real and what is not. Symptoms of psychosis include delusions (false beliefs) and hallucinations (seeing or hearing things that others do not see or hear). Other symptoms include incoherent or nonsense speech, and behavior that is inappropriate for the situation.”

It may or may not be a symptom of mental illness, such as schizophrenia or bipolar disorder. And it can be hard to spot, with many people who experience a first episode having symptoms for more than a year before anyone figures it out and they get treatment, according to the NIMH. And “the bad news,” wrote NIMH director Thomas Insel in a 2014 blog post, “is that we don’t yet have an intervention proven to prevent psychosis in those at risk.”

De Grood was one of those who went unspotted until it was too late. Sure, there was a strange Facebook post, a reference to a rock band and a song, but it was like a million other posts about rock bands, with nothing obviously threatening, except in hindsight. Indeed, he seemed to have everything to look forward to, and little to regret.

He held a job at the local Safeway and had given his employers no reason to suspect there was anything dreadfully wrong when he headed over to Segura’s rented house for the party, though witnesses at Safeway said he was “not looking well,” according to Zedkova’s psychiatric report. Before leaving, according to the statement of facts, he bought a box cutter to take with him.

It later was revealed that he had “purchased garlic to protect himself because the vampires and werewolves were on the side of evil,” Zedkova wrote in her report to the court.

The sequence of events after he left the Safeway is drawn from the court statements of two psychiatrists, including Zedkova, and a statement of facts that was read aloud in court by the prosecutor and agreed to by the defense attorney, as described in the Canadian press, including CTV news, the Toronto Star, the CBC and Global News.

Once at the party, witnesses would later tell police, de Grood did indeed turn “weird.” He spoke of “vampires” and of “getting ready for the big apocalypse.”

And he texted odd, frightening, messages that made little sense.

To his parents: “I’m OK, mom. I promise.” “You can’t come here or you will die.” “I promise I’m coming home ASAP.”

To the Safeway manager: “ Trust that I never hurt anyone.” “All will be known” and the number “5,” with no further explanation.

“Are you OK?” his father responded. “I am very concerned about your incoherent ramblings.”

“Illuminati,” his son responded. “Mary doesn’t have to die this time operation mind crime to American soldier.”

Illuminati? Why the reference to the “ Ancient and Illuminated Seers of Bavaria,” a Masonic offshoot, which, like the Masons, have a cherished place in the sometimes deranged literature of conspiracy and paranoia.

“You’re sounding like you are losing your mental faculties,” his father replied.

“Hey,” his father texted, “where are you. . .[don’t] do anything rash. We love you.”

To that, there was no reply. By that time, according to testimony and evidence at his trial over the past week, he had begun to do something so rash there was nothing left to say, nothing that could be said.

“Around 12:30 a.m.” on April 15, as the CBC reported, “some of the party guests were gathered around a fire outside when Riley Lindenaar saw de Grood place his cellphone on an axe blade and drop it in the fire. Lindenaar got the phone out of fire but de Grood grabbed it, smashed it with the axe and threw it away with no explanation. Brendan McCabe said de Grood complained that his parents thought he was going insane and wanted him to get help and go on medication. He also said the end of the world was coming at midnight and spoke of ‘purification” and ‘jihad.’ ”

Around 1 a.m. McCabe left the house with three others to get food at McDonald’s.

De Grood engaged in a conversation with Zachariah Rothwell and “began to believe” he was a “werewolf as they discussed the end of the world. He indicated that he felt Zachariah was arguing with him but he felt immediately threatened when he said ‘maybe you’ll die before me’ to Mr. De Grood,” Zedkova stated. “It was at this point” that he went to the kitchen “to grab the knife before Zachariah could attack him. He believed that this was the only way to kill a werewolf.”

He then went after the others, telling Zedkova that “the four other victims were attacked because he felt that they were part of the conspiracy,” the report said, because “earlier in the evening they had snubbed him.” And besides, “he had heard a male voice, who he thought was the devil, telling him to ‘kill them before they get you.’ ”

Which he did.

That crowd at the party had dwindled from 20 or 15 to a handful. In all, de Grood stabbed and killed five party-goers, including Segura, a total of 22 times. It was the worst mass killing in Calgary’s history, drawing worldwide attention in part because these things don’t happen there.

The examinations psychiatrists presented at the trial have offered a rare window into the mind of a mass killer. What the young people at the party didn’t know, couldn’t have known, was that a monster had materialized in their midst.

The statement, read by Crown prosecutor Neil Wiberg, said de Grood stabbed the victims quickly, according to CTV news, the Toronto Star and the CBC.

“I just want to say that when I stabbed them, I tried to do it mercifully,” de Grood was quoted as saying in the statement. “I aimed for their heart. They put up a struggle, which made it hard but, so you know, it wasn’t sadistic or anything,” de Grood is quoted telling police officers.

“What I did may seem atrocious but I was killing Medusas, werewolves.”

When the others returned to the house from McDonald’s about 20 minutes later, they heard screaming, according to the statement as reported by the CBC. “Hunter came running out of the house with de Grood chasing after him. Hunter told them de Grood had a knife, before collapsing on the front lawn, where friends began trying to save his life.

“De Grood’s hands and his knife were covered in blood. ‘It’s the night of the long knives,’ de Grood said, before taking off on foot, running.”

Brendan McCabe, a boyhood friend who had brought de Grood to the party, chased him and caught up with him, shoving him against a parked truck. De Grood wiped his bloody hands on McCabe and said they were “blood brothers.”

Then de Grood reached into his pocket for a box cutter he’d brought from work and told McCabe to back off or he’d be next.

“McCabe complied,” as the CBC reported, “and returned to the house where Hunter was clinging to life on the front lawn. Inside, Segura, Rathwell and Hong were already dead. Perras was also critically wounded, and friends were trying frantically to save her and Hunter.”

De Grood ran again. Police tracked him with a police dog, which brought him to the ground. In the ambulance, he reportedly declared himself “the son of God,” “born in an incubator” and an “alien.”

He wasn’t just “losing his mental faculties,” as his father suspected, the psychiatrists testified last week. He had already lost them. De Grood, had suffered a psychotic episode — his first, as far as they knew, as he had no prior history and no diagnosed mental illness.

His delusional state was deep and deeply dangerous. That full moon, so dazzling to the Northern Hemisphere, was to him a sign that the world was coming to an end, psychiatrists said in their reports.

Others at the party, in his mind, were werewolves who he felt compelled to destroy. His twisted brain harbored illusions of a sinister albeit incoherent conspiracy. Neither de Grood nor the doctors were sure when it all started, when his “thinking changed,” as Zedkova reported. It may have been at least two weeks prior to the crimes, but he kept it well hidden.

It was an odd assortment of conspirators to be sure, but not so odd that your can’t find similar linkages described on the internet as Robert Todd Carroll writes in the Skeptics Dictionary:

The Illuminati “were members of a secret society in Bavaria in the late 18th century. They had a political agenda that included republicanism and abolition of monarchies, which they tried to institute by means of subterfuge, secrecy, and conspiracy, including the infiltration of other organizations. They fancied themselves to be ‘enlightened’ but they had little success and were destroyed within fifteen years of their origin...Paranoid conspiracy theorists (PCTs) believe the Illuminati cabal still exists, either in its original form or as a paradigm for later cabals.” Many PCTs believe “that large Jewish banking families have been orchestrating various political revolutions and machinations throughout Europe and America since the late eighteenth century, with the ultimate aim of bringing about a satanic New World Order. What George Bush was talking about in his state of the union address in 1991 was no less than the establishment of a single world government with the anti-Christ (who some say is Bill Clinton (or is he a decoy?), but could be Pat Robertson or George W. Bush or Barack Obama ) at its head...There are several ‘sects’ of PCTs...They each think the others are evil or nuts but their paranoia has the same focus: the end is near.”

But de Grood was no mere conspiracy theorist, as both psychiatrists agreed. Based on their examinations of him, he was at that moment psychotic.

“Mr. De Grood,” the Zedkova report continued, “recounted that on 14 April he went to work as usual but had known the world was going to end that day. He purchased garlic to protect himself because the vampires and werewolves were on the side of the evil. He admitted in our interview that his beliefs about werewolves came from the movie series, Twilight, and his beliefs about vampires came from his reading the graphic novel Cirque du Freak...He believed he need to wear gloves and a box cutter that night because it was his job to dismember the bodies from the war that was at hand and to dispose the bodies before the police arrived because the police were part of the conspiracy.” De Grood told psychiatrists he wasn’t sure when the war would begin.

But the exchange, an argument with another party-goer, Zacharia, convinced him that it had.

His future will soon be in the hands of a judge. “What they will have to show is the accused didn’t appreciate...or didn’t know what he was doing was morally wrong,” Michael Nesbitt, of the University of Calgary Law School, told the CBC. “So really, what it’s going to be about is his capacity to understand either what he was doing would result in death or to understand that what he was doing was wrong.” If the court finds de Grood not criminally responsible, it would likely order him hospitalized, though it could send him home under restrictions.

Zedhkova and a second psychiatrist, Alberto Choy, both said that they believed de Grood should be found not criminally responsible. “In my opinion,” wrote Choy, “it is more likely than not that Mr. De Grood appreciated the nature and quality of his acts in stabbing his victims...However, it is my opinion that, more likely than not, Mr. De Grood did not know, or even appreciate, that his behavior was morally wrong because he was operating under a delusion that he was being threatened at the time.”